Aims. The aim of this study was to compare the
Aims. The hip’s capsular ligaments passively restrain extreme range of movement (ROM) by wrapping around the native femoral head/neck. We determined the effect of hip resurfacing arthroplasty (HRA), dual-mobility total hip arthroplasty (DM-THA), conventional THA, and surgical approach on ligament function. Materials and Methods. Eight paired cadaveric hip joints were skeletonized but retained the hip capsule. Capsular ROM restraint during controlled internal rotation (IR) and external rotation (ER) was measured before and after HRA, DM-THA, and conventional THA, with a posterior (right hips) and anterior capsulotomy (left hips). Results. Hip resurfacing provided a near-native ROM with between 5° to 17° increase in IR/ER ROM compared with the native hip for the different positions tested, which was a 9% to 33% increase. DM-THA generated a 9° to 61° (18% to 121%) increase in ROM. Conventional THA generated a 52° to 100° (94% to 199%) increase in ROM. Thus, for conventional THA, the capsule function that exerts a limit on ROM is lost. It is restored to some extent by DM-THA, and almost fully restored by hip resurfacing. In positions of low flexion/extension, the posterior capsulotomy provided more normal function than the anterior, possibly because the capsule was shortened during posterior repair. However, in deep flexion positions, the anterior capsulotomy functioned better. Conclusion. Native head-size and capsular repair preserves capsular function after arthroplasty. The anterior and posterior approach differentially affect postoperative
Understanding spinopelvic mechanics is important for the success of total hip arthroplasty (THA). Despite significant advancements in appreciating spinopelvic balance, numerous challenges remain. It is crucial to recognize the individual variability and postoperative changes in spinopelvic parameters and their consequential impact on prosthetic component positioning to mitigate the risk of dislocation and enhance postoperative outcomes. This review describes the integration of advanced diagnostic approaches, enhanced technology, implant considerations, and surgical planning, all tailored to the unique anatomy and
Aims. It has been well documented in the arthroplasty literature that lumbar degenerative disc disease (DDD) contributes to abnormal spinopelvic motion. However, the relationship between the severity or pattern of hip osteoarthritis (OA) as measured on an anteroposterior (AP) pelvic view and spinopelvic
The advent of modular porous metal augments has ushered in a new form of treatment for acetabular bone loss. The function of an augment can be seen as reducing the size of a defect or reconstituting the anterosuperior/posteroinferior columns and/or allowing supplementary fixation. Depending on the function of the augment, the surgeon can decide on the sequence of introduction of the hemispherical shell, before or after the augment. Augments should always, however, be used with cement to form a unit with the acetabular component. Given their versatility, augments also allow the use of a hemispherical shell in a position that restores the centre of rotation and
There are three basic concepts that are important to the
The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA). This prospective study included 140 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess study outcomes pre- and post-ACL resection with knee extension and 90° knee flexion. This study included 76 males (54.3%) and 64 females (45.7%) with a mean age of 64.1 years (SD 6.8) at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1° varus (SD 4.6° varus).Aims
Methods
A consecutive series of 150 patients with clavicular fractures is presented. In 81% detailed information regarding the mechanism of the injury was available and, of these, 94% had fractured their clavicle from a direct blow on the shoulder; only 6% had fallen on the outstretched hand. This finding, at variance with commonly held views regarding the mechanism of this injury, was further investigated by
The purpose of this study was to test the hypothesis that patella alta leads to a less favourable situation in terms of patellofemoral contact force, contact area and contact pressure than the normal patellar position, and thereby gives rise to anterior knee pain. A dynamic knee simulator system based on the Oxford rig and allowing six degrees of freedom was adapted in order to simulate and record the dynamic loads during a knee squat from 30° to 120° flexion under physiological conditions. Five different configurations were studied, with variable predetermined patellar heights. The patellofemoral contact force increased with increasing knee flexion until contact occurred between the quadriceps tendon and the femoral trochlea, inducing load sharing. Patella alta caused a delay of this contact until deeper flexion. As a consequence, the maximal patellofemoral contact force and contact pressure increased significantly with increasing patellar height (p <
0.01). Patella alta was associated with the highest maximal patellofemoral contact force and contact pressure. When averaged across all flexion angles, a normal patellar position was associated with the lowest contact pressures. Our results indicate that there is a
The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery. A total of 76 patients (34 bi-UKA and 42 TKA patients) were analyzed in a prospective, single-centre, randomized controlled trial. Flat ground shod gait analysis was performed preoperatively and one year postoperatively. Knee flexion moment was calculated from motion capture markers and force plates. The same setup determined proprioception outcomes during a joint position sense test and one-leg standing. Surgery allocation, surgeon, and secondary outcomes were analyzed for prediction of the primary outcome from a binary regression model.Aims
Methods
This animal study compares different methods
of performing an osteotomy, including using an Erbium-doped Yttrium
Aluminum Garnet laser, histologically, radiologically and
A study was made of the mechanics of blood-bearing in a series of patients treated with a cast-brace for fracture of the distal femur. Knee hinges incorporating strain-gauges, a simple force-plate on the floor and a standardised weight-bearing test were used to record axial loads through the cast-brace itself and through the fracture during the phases of healing. The cast-brace carried loads of only 10 to 20 per cent of body weight and functioned mainly as an antibuckling hinged tube. Patterns of weight-bearing recovery showed that the fracture itself limited loads to safe levels. A measure of the recovery of strength at the fracture was determined and termed the "fracture load index". Graphs obtained in this way demonstrated four
This paper presents a prospective trial carried out using the Monk "soft top" endoprosthesis in 33 patients. Two years after operation 70 per cent of the remaining patients had pain. A
The aim of this study was to compare the peak pull-out force
(PPF) of pedicle-lengthening screws (PLS) and traditional pedicle
screws (TPS) using instant and cyclic fatigue testing. A total of 60 lumbar vertebrae were divided into six groups:
PLS submitted to instant pull-out and fatigue-resistance testing
(groups A1 and A2, respectively), TPS submitted to instant pull-out
and fatigue-resistance testing (groups B1 and B2, respectively)
and PLS augmented with 2 ml polymethylmethacrylate, submitted to
instant pull-out and fatigue-resistance testing (groups C1 and C2,
respectively). The PPF and normalized PPF (PPFn) for bone mineral density
(BMD) were compared within and between all groups.Aims
Materials and Methods
We evaluated the
We performed a
Repeated trauma to the radial head may be one of the causative factors in the genesis of osteochondritis dissecans of the capitellum. We measured the force, contact area and pressure across the radiocapitellar articulation of the elbow before and after radial shortening osteotomy in five fresh-frozen cadaver upper limbs with loads of 45, 90 and 135 N, respectively. Measurements were made on pressure-sensitive film placed in the radiocapitellar articulation with the forearm in the supinated, neutral and pronated positions before and after radial shortening. Radial shortening significantly reduced the mean force and contact area across the radiocapitellar articulation in all positions of the forearm.
We examined the effect of the Gamma nail on strain distribution in the proximal femur, using ten cadaver femora instrumented with six unidirectional strain gauges along the medial and lateral cortices. The femora were loaded to 1800 N and strains were determined with or without distal interlocking screws before and after experimentally created two-part and four-part fractures. Motion of the sliding screw and the nail was also determined. Strain patterns and screw motion were compared with previously obtained values for a sliding hip screw device (SHS). The Gamma nail was shown to transmit decreasing load to the calcar with decreasing fracture stability, such that virtually no strain on the bone was seen in four-part fractures with the posteromedial fragment removed; increasing compression was noted, however, at the proximal lateral cortex. Conversely, the SHS showed increased calcar compression with decreasing fracture stability. The insertion of distal interlocking screws did not change the pattern of proximal femoral strain. The Gamma nail imparts non-physiological strains to the proximal femur, probably because of its inherent stiffness. These strains may alter bone remodelling and interfere with healing. Distal interlocking screws may not be necessary for stable intertrochanteric fractures.
The use of prolonged halo stabilisation in a child is increasingly indicated for trauma and congenital instability of the cervical spine, but complications of pin fixation in this age group are frequent. We have analysed four aspects of the mechanics of the halo pin: the forces applied by each of six surgeons was shown to vary widely, penetration of the inner table occurred relatively easily, friction at the pin-halo interface influenced forces, and the skull thickness measured by CT scan varied from 1.1 mm to 4.3 mm in children under six years of age. We recommend CT scanning of the skull before elective halo application in young children to ascertain the safest pin sites.
The effects of advancement of the tibial tuberosity by inserting bony wedges was studied on cadaveric specimens of the knee. The geometry, the contact areas and the forces acting on the patellofemoral joint were investigated, and the forces acting on the tibiofemoral compartment were calculated. A 1 cm advancement was found to be optimal in reducing the high patellofemoral joint forces occurring at 90 degrees and 110 degrees of flexion, whilst causing least reduction of the contact areas; the stresses on the joint were reduced significantly. Advancement by 2 cm and by 3 cm drastically reduced the congruity and the size of the contact area. It was also shown that 2 cm and 3 cm advancement caused an increase in forces at the patellofemoral joint and also in the tibiofemoral joint in a direction tangential to the articular surfaces.
The aim of this study was to examine the loading
of the other joints of the lower limb in patients with unilateral osteoarthritis
(OA) of the knee. We recruited 20 patients with no other symptoms
or deformity in the lower limbs from a consecutive cohort of patients
awaiting knee replacement. Gait analysis and electromyographic recordings were
performed to determine moments at both knees and hips, and contraction
patterns in the medial and lateral quadriceps and hamstrings bilaterally.
The speed of gait was reduced in the group with OA compared with
the controls, but there were only minor differences in stance times
between the limbs. Patients with OA of the knee had significant
increases in adduction moment impulse at both knees and the contralateral
hip (adjusted p-values: affected knee: p <
0.01, unaffected knee
p = 0.048, contralateral hip p = 0.03), and significantly increased
muscular co-contraction bilaterally compared with controls (all
comparisons for co-contraction, p <
0.01). The other major weight-bearing joints are at risk from abnormal
biomechanics in patients with unilateral OA of the knee. Cite this article:
We compared the bulking and tensile strength of the Pennington modified Kessler, Cruciate and the Savage repairs in an
The anterior cruciate ligament was replaced in rabbits, using implants of carbon or polyester filaments with known mechanical properties. The biocompatibility of the implants was assessed in detail using light microscopy, and scanning and transmission electron microscopy. Mechanical tests were made of stability, in comparison with normal joints and controls after excision of the ligament. Some carbon fibre implants broke down in vivo, allowing instability; the fragments caused chronic inflammation. Intact carbon implants did not induce the formation of neoligaments; they were covered by tissue, but there was no ingrowth. Polyester did not degrade mechanically and supported early collagenous ingrowth within the implant, even in the mid-joint space. It was concluded that there was no justification for the use of carbon fibres as anterior cruciate replacements; polyester appeared to be suitable.
The off-loading characteristics of the cast-braces of 30 patients with fractures of the shaft of the femur have been investigated, during axial loading, using strain-gauge transducers. These were applied at the level of the fracture, where the cast was circumferentially split, and to the hinges of the brace at the knee. They measured the load transferred between the two portions of the thigh cast, and between the thigh cast as a whole and the below-knee cast; by subtraction from the total load on the limb, the skeletal force at the fracture level and at the knee could be calculated. In all patients there was an increase in the fracture load as union progressed which was thought to be due to physiological feedback mechanism from the fracture site. The load carried by the two portions of the thigh cast and by the thigh cast as a whole was proportionately high at first and stabilised at an average of 35 per cent of body weight.
In 65 mature Wistar rats a Kirschner wire was introduced into the medullary cavity of each femur. A closed transverse mid-shaft fracture of one femur was produced by a three-point bending technique. Subsequently the mechanical characteristics of the healing fracture, including the torque and angle of twist required to take the callus to its yield point and to ultimate failure, were compared with those for the opposite femur of each rat. Controls were killed in groups at two, three, four, five and seven weeks. Test animals were given bovine growth hormone in a daily dose of five milligrams before being killed in groups at two, three and four weeks. A significant increase in torque index was found in the two-week group of test animals but not in subsequent groups. No evidence was found that growth hormone given alone could produce an overall shortening of the healing time in fresh fractures.
Nine patients with nonunited humeral shaft fractures were treated by open reduction and internal fixation with an intramedullary fibular bone graft and a compression plate. Fixation of the screws was enhanced by passing them through the fibula as well as the two humeral cortices (quadricortical fixation). Eight of the nine fractures united at an average of 3.5 months. Tests on cadaver bones showed that quadricortical fixation was as strong as methylmethacrylate augmentation and significantly better than bicortical fixation.
Using 26 cadaver shoulders, we produced a standard defect in the supraspinatus tendon and performed one of three types of repair. Their strength was found by testing in tension the force required to produce a gap of 3 mm, then 6 mm, and finally total disruption of the repair. The use of a polyethylene patch to spread the forces over the lateral bone surface and of extra sutures to grasp the tendon end raised by 2.6 times the load at which a 3 mm gap in the repair occurred and by 1.7 times the load to failure.
A leading problem with cementless hip replacement is thigh pain, probably due to some degree of loosening. This is most pronounced during activities such as stair climbing or getting up from a chair. Our study compares the immediate fixation of three stems in widespread clinical use, using a cadaver test simulation in which the femur was horizontal, and cyclic forces acted vertically downward on the prosthetic head with gradual increments of load. We implanted and tested 18 pairs of femurs, making analyses between stem types by right to left comparisons. We found no statistically significant differences in loosening between cementless AML and PCA prostheses, but cemented stems withstood greater loads than uncemented stems by a factor of five or more.
To investigate the origin of fractures at the distal locking site of the Gamma nail, we loaded ten paired human cadaver femora fixed with a Gamma nail in torsion until they fractured. When an awl was hammered in to start the hole for distal locking a fissure appeared in the lateral cortex of all the femora, and the mean torsional load to create a fracture was reduced by 57.8% compared with that in a control group in which the distal locking hole had been started with a centre drill. When an additional drill hole was made, the mean failure load in torsion decreased by 35.7%. We strongly recommend that an awl should not be used at the distal locking site of the Gamma nail; we recommend the use of a centre drill. Additional drill holes should be avoided because they act as stress raisers.
A cadaver study was performed to determine the effect of arm position and capsular release on rotator cuff repair. Artificial defects were made in the rotator cuff to include only the supraspinatus (small) or both supraspinatus and infraspinatus (large). The defects were repaired in a standard manner with the shoulder abducted 30 degrees at the glenohumeral joint. Strain gauges were placed on the lateral cortex of the greater tuberosity and measurements were recorded in 36 different combinations of abduction, flexion/extension, and medial/lateral rotation. Readings were obtained before and after capsular release. With small tears, tension in the repair increased significantly with movement from 30 degrees to 15 degrees of abduction (p <
0.01) but was minimally affected by changes in flexion or rotation. Capsular release significantly reduced the force (p <
0.01) at 0 degree and 15 degrees abduction. For large tears, abduction of 30 degrees or more with lateral rotation and extension consistently produced the lowest values. Capsular release resulted in 30% less force at 0 degree abduction (p <
0.05).
We report the experimental use of three different biological implants to restore articular surface defects: glutaraldehyde-fixed bovine meniscal xenograft, glutaraldehyde-fixed bovine costal cartilage xenograft, and viable osteochondral allografts. The grafts were implanted in the knees of 19 goats who were allowed free-field activity and were studied for up to one year. The natural articular surfaces of meniscal fibrocartilage provided excellent articular surfaces at all times. Equally good articular surfaces were restored by host tissue growth covering costal cartilage grafts at six months, but by 12 months this surface had degenerated. The majority of the allografts survived and integrated with the host at six months, but many showed signs of failure at 12 months. Only three out of seven ungrafted defects healed completely at six months and the healed surfaces were degenerating at 12 months.
The aim of this study was to compare the maximum
laxity conferred by the cruciate-retaining (CR) and posterior-stabilised
(PS) Triathlon single-radius total knee arthroplasty (TKA) for anterior
drawer, varus–valgus opening and rotation in eight cadaver knees
through a defined arc of flexion (0º to 110º). The null hypothesis
was that the limits of laxity of CR- and PS-TKAs are not significantly
different. The investigation was undertaken in eight loaded cadaver knees
undergoing subjective stress testing using a measurement rig. Firstly
the native knee was tested prior to preparation for CR-TKA and subsequently
for PS-TKA implantation. Surgical navigation was used to track maximal
displacements/rotations at 0º, 30º, 60º, 90º and 110° of flexion.
Mixed-effects modelling was used to define the behaviour of the
TKAs. The laxity measured for the CR- and PS-TKAs revealed no statistically
significant differences over the studied flexion arc for the two
versions of TKA. Compared with the native knee both TKAs exhibited
slightly increased anterior drawer and decreased varus-valgus and
internal-external roational laxities. We believe further study is required
to define the clinical states for which the additional constraint
offered by a PS-TKA implant may be beneficial. Cite this article:
In vitamin D-fed chicks 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 were implanted into experimentally-produced fractures of the mid-tibia. The mechanical and biochemical properties of the tibia were evaluated for two weeks, including torsion tests, measurement of alkaline phosphatase activity, 45Ca incorporation, and Ca2+ content. Both dihydroxylated metabolites of vitamin D3 had a direct effect on endochondral bone formation. 24,25(OH)2D3 strengthened the callus, and raised alkaline phosphate activity in the first seven days after fracture. 1,25(OH)2D3 decreased the strength of the callus concomitant with a reduction in 45Ca incorporation. It is suggested that local application of 24,25(OH)2D3 into fractures may accelerate healing and prevent non-union.
Excessive foot pronation has been considered to be related to anterior knee pain. We undertook a prospective study to test the hypothesis that exertional anterior knee pain is related to the static and dynamic parameters of foot pronation. Two weeks before beginning basic training lasting for 14 weeks, 473 infantry recruits were enrolled into the study and underwent two-dimensional measurement of their subtalar joint displacement angle during walking on a treadmill. Of the 405 soldiers who finished the training 61 (15%) developed exertional anterior knee pain. No consistent association was found between the incidence of anterior knee pain and any of the parameters of foot pronation. While a statistically significant association was found between anterior knee pain and pronation velocity (left foot, p = 0.05; right foot, p = 0.007), the relationship was contradictory for the right and left foot. Our study does not support the hypothesis that anterior knee pain is related to excessive foot pronation.
Aims. The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population. Methods. We used an active appearance model-based approach to segment the preoperative CT of 21 osteoarthritic patients, which identified the osteophyte-free surfaces and estimated cartilage from the segmented bones; these geometries were used to construct patient-specific musculoskeletal models of the pre-diseased knee. Subsequently, implantations were simulated using the MA method, and a previously developed optimization technique was employed to find the optimal implant position that minimized the root mean square deviation between pre-diseased and postoperative ligament strains and kinematics. Results. There were evident
Aims. Spinopelvic pathology increases the risk for instability following total hip arthroplasty (THA), yet few studies have evaluated how pathology varies with age or sex. The aims of this study were: 1) to report differences in spinopelvic parameters with advancing age and between the sexes; and 2) to determine variation in the prevalence of THA instability risk factors with advancing age. Methods. A multicentre database with preoperative imaging for 15,830 THA patients was reviewed. Spinopelvic parameter measurements were made by experienced engineers, including anterior pelvic plane tilt (APPT), spinopelvic tilt (SPT), sacral slope (SS), lumbar lordosis (LL), and pelvic incidence (PI). Lumbar flexion (LF), sagittal spinal deformity, and hip user index (HUI) were calculated using parameter measurements. Results. With advancing age, patients demonstrate increased posterior APPT, decreased standing LL, decreased LF, higher pelvic incidence minus lumbar lordosis (PI-LL) mismatch, higher prevalence of abnormal spinopelvic mobility, and higher HUI percentage. With each decade, APPT progressed posteriorly 2.1°, LF declined 6.0°, PI-LL mismatch increased 2.9°, and spinopelvic mobility increased 3.8°. Significant differences were found between the sexes for APPT, SPT, SS, LL, and LF, but were not felt to be clinically relevant. Conclusion. With advancing age, spinopelvic
Rotator cuff pathology is the main cause of shoulder pain and dysfunction in older adults. When a rotator cuff tear involves the subscapularis tendon, the symptoms are usually more severe and the prognosis after surgery must be guarded. Isolated subscapularis tears represent 18% of all rotator cuff tears and arthroscopic repair is a good alternative primary treatment. However, when the tendon is deemed irreparable, tendon transfers are the only option for younger or high-functioning patients. The aim of this review is to describe the indications,
Lisfranc injuries were previously described as fracture-dislocations of the tarsometatarsal joints. With advancements in modern imaging, subtle Lisfranc injuries are now more frequently recognized, revealing that their true incidence is much higher than previously thought. Injury patterns can vary widely in severity and anatomy. Early diagnosis and treatment are essential to achieve good outcomes. The original classification systems were anatomy-based, and limited as tools for guiding treatment. The current review, using the best available evidence, instead introduces a stability-based classification system, with weightbearing radiographs and CT serving as key diagnostic tools. Stable injuries generally have good outcomes with nonoperative management, most reliably treated with immobilization and non-weightbearing for six weeks. Displaced or comminuted injuries require surgical intervention, with open reduction and internal fixation (ORIF) being the most common approach, with a consensus towards bridge plating. While ORIF generally achieves satisfactory results, its effectiveness can vary, particularly in high-energy injuries. Primary arthrodesis remains niche for the treatment of acute injuries, but may offer benefits such as lower rates of post-traumatic arthritis and hardware removal. Novel fixation techniques, including suture button fixation, aim to provide flexible stabilization, which theoretically could improve midfoot
Aims. Achieving accurate implant positioning and restoring native hip
Aims. Refobacin Bone Cement R and Palacos R + G bone cement were introduced to replace the original cement Refobacin Palacos R in 2005. Both cements were assumed to behave in a
Aims. Acute and chronic injuries of the interosseus membrane can result in longitudinal instability of the forearm. Reconstruction of the central band of the interosseus membrane can help to restore
Aims. The aim of this study was to determine the immediate post-fixation stability of a distal tibial fracture fixed with an intramedullary nail using a
